I have E3 flasher and installed it correctly. Now do i have to open PS3 again for this fast dual thing?
E3 team say in their manual "One key fast dual boot operation need a wire to be cut on mainboard" and "solder A point to somewhere".
Is that necessary? or is it just for some models?
anyone who has done it and know it?

each console has a unique console key, if the nor backup you was corrupted in anyway and you attempted a downgrade without checking the backup using Flowrebuilder. the console is bricked for good!

its not possible to unbrick the console using a nor backup from any other ps3 cause each console has a unique key, even if you make 1000x nor dumps if the first one is corrupted the same flaw will be duplicated in every dump you make.

you should have checked to make sure that your nor backup was not corrupted using flowrebuilder before attempting to downgrade..